Psychosocial measures

3.5.1 Depressive symptoms and use of antidepressant medication, Studies I & III

Depressive symptoms refer to wide range of mental problems, including emotional, cognitive, behavioral and physical symptoms. Most epidemiological studies use self- report questionnaires to assess depressive symptoms and to identify persons with perceived mental stress. Self-reports are less expensive and less time-consuming than interviews and therefore more practical for research use. In order to measure depressive symptoms in studies I & III, participants filled in the SF-36/RAND-36 questionnaire (Hays, Sherbourne, & Mazel, 1993) containing nine items of depressive symptoms. The Mental Health Index (MHI), a subscale of SF-36, is used to capture four major dimensions of mental health: anxiety, depression, loss of behavioral/emotional control, and psychological well-being (Hays et al., 1993), and the scale has been shown to have high sensitivity and specificity for detecting clinical depression (Berwick et al., 1991). However, a Finnish validation study of SF-36 found that the Vitality Scale (VS) items correlate positively with MHI, and concluded that the VS items are also important in capturing depression in a Finnish population (A. Aalto, Aro, & Teperi, 1999). A similar observation has been made in a French population (Perneger, Leplege, Etter, & Rougemont, 1995). Therefore, items of the MHI and the VS were summed (after reverse scoring the positive items) to measure depressive symptoms on a scale asking

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participants how much of the time during the preceding four weeks they felt full of life, nervous, happy, calm and peaceful, worn out, full of energy, downhearted and blue, tired, or so down nothing could cheer them up. The items were rated on a six-point scale (not at all, on very few occasions, some of the time, good part of the time, most of the time, all of the time). The reliability for these items was high (Cronbach’s = 0.89) and a factor analysis (using an eigenvalue criterion of one) of the items supported a unidimensional, single-scale solution (data not shown). MHI and VS were also significantly correlated (r = 0.70, P < 0.001). When using the sum variable in analysis, it was standardized according to sex and log-transformed.

The use of antidepressant medication was self-reported in a questionnaire and confirmed in an interview by a research nurse specifying the type of medication they used. In study I, when participants with either established or newly diagnosed diabetes (diagnosis based on OGTT) were excluded, the number of participants using antidepressant medication was: SSRI/SNRI medication (n = 98), TCA medication (n = 36), TCA and SSRI/SNRI medication (n = 10), and antidepressant medication not specified (n = 3) as an indicator of use of antidepressant medication (n = 147, 110 women and 37 men). In study III, current use of SSRI/SNRI medication (n = 116), TCA medication (n = 43), and TCA and SSRI/SNRI (n = 11) were considered as an indicator of use of antidepressant medication. In addition, information on 4 participants’ type of medication was insufficient. In total 174 participants, 132 women and 42 men, reported using one or more products of antidepressant medication.

3.5.2 Subjective sleep complaints, Study II

Complaints related to sleep apnea, insomnia and daytime sleepiness were derived from the self-reported questionnaire, the Basic Nordic Sleep Questionnaire (BNSQ) (Partinen & Gislason, 1995). The following three questions addressed sleep apnea: 1. Do you snore while sleep (ask other people if you do not know)? 2. How do you snore (ask other people about the quality of your snoring)? 3. Have you had breathing pauses at sleep (have other people noticed that you have pauses in your respiration when you sleep)? The following three questions addressed insomnia: 1. Have you had difficulties

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in falling asleep the past three months?, 2. How often have you awakened during the night the past three months?, 3. If you use to wake up during the night, how many times do you usually wake up during one night (during the past three months)? Daytime sleepiness was measured with the following three questions: 1. Do you feel excessively sleepy in the morning after awakening? 2. Do you feel excessively sleepy during daytime? 3. How often do you sleep naps at daytime?

The questions were answered by using a quantitative scale ranging from never or less than once per month (1), less than once per week (2), on one-two days/nights per week (3), on three-five days/nights per week (4) to every day/night or almost every day/night per week (5); except, the quality of snoring was assessed using a qualitative scale ranging from “I don’t snore” (1), “my snoring sounds regular and it is of low voice” (2), “it sounds regular, but rather loud” (3), “it sounds regular but very loud (other people hear my snoring in the next room)” (4) to “I snore very loud and intermittently (there are silent breathing pauses when snoring is not heard and at times very loud snorts with gasping)” (5), and frequency of awakenings during one night was assessed using a quantitative scale ranging from usually “I do not wake up at night” (1), once per night (2), two times (3), three-four times (4) to at least five times per night (5).

Answers to questions on sleep apnea, insomnia and daytime sleepiness were summed and the top quartile was used as a cut-off for identifying individuals with more frequent/ severe complaints. The group whose complaints of sleep apnea, insomnia and daytime sleepiness fell below the top quartile and who in addition reported using no sleeping pills ( 9.4%, n = 75, reported using sleeping pills) was used as the reference group (from here on referred to as ‘No or minor sleep complaints’).

3.5.3 Stressful life events, Study IV

The subjects completed a questionnaire consisting of 15 stressful life events (Table 4). All questions concerned life events known to be major stressors (Brugha et al., 1985; Mooy et al., 2000; Rahe et al., 1973; Räikkönen et al., 2007). The subjects were asked to evaluate the occurrence and stressfulness of these events (0 = not occurred, 1 = not at

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all stressful, 2 = mildly stressful, 3 = moderately stressful, 4= extremely stressful) during the past 12 months. For the analyses, the measurement scale was dichotomized by contrasting moderately and extremely stressful events with events that were not at all or mildly stressful or had not occurred at all (Räikkönen et al., 2007). These items encompassed stressful events arising from five different domains: finance, work, social relationships, health and housing. Reliability of these items measured with the Cronbach’s was 0.76.

Table 4. Items of stressful life events questionnaire and their domains.